<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>激活</title>
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <style>
        .active-box {
            display: flex;
            flex-direction: column;
            align-items: center;
            position: absolute;
            left: 50%;
            top: 20%;
            transform: translate(-50%, -50%);
            row-gap: 40px;
        }

        .form-control {
            height: 50px;
            width: 700px;
            font-size: 20px;
            border-radius: 25px;
        }

        .btn {
            flex-grow: 0;
            width: 700px;
            height: 50px;
            border-radius: 25px;
        }
    </style>
</head>
<body>
<div class="active-box">
    <input type="text" class="form-control" placeholder="请输入激活码" aria-describedby="sizing-addon1">
    <button type="button" class="btn btn-info">立即激活</button>
</div>
</body>
</html>